The Toxicology Graduate Program at the University of Arizona has a long-standing reputation for excellence in training Ph.D. scientist. Many of our graduates are now leaders in academia, industry, and government. Current trainees are now selected through a University-wide competition. The graduate program has evolved from a systems-based toxicology experience to training students to apply state-of-the art techniques to solve mechanisms of environmental toxicity affecting complex diseases in various organ systems. The cutting-edge basic science research programs of 22 Training Grant Faculty members, state-of-the-art technologies developed at the University of Arizona in association with the Southwest Environmental Health Sciences Center and Bio5, and translational approaches undertaken by our NIEHS Superfund Program and US-Mexico Binational Center provide an exceptionally stimulating environment for the training of graduate students and postdoctoral fellows. The interactive research of our Training Grant Faculty and our state-of-the-art Facility Cores extend the training environment from a single laboratory-oriented domain into a multidisciplinary experience strongly supportive of collaborative research. The University provides financial support for first year Ph.D. students, providing a large pool of highly qualified candidates for competitive selection of predoctoral trainees. Predoctoral training is achieved through a combination of coursework, laboratory research, and supplemental enrichment activities. Postdoctoral trainees participate in innovative research programs and are guided to develop professional skills in oral and written communication and in supervision. Over past five years, the curricular changes parallel the evolving expertise of the Training Grant Faculty in utilizing state-of-the-art technology for research projects. We have recruited 3 senior (Professor) and 3 junior (Assistant Professor) faculty into the Training Grant, which significantly enhances the strength in the core of mechanistic based molecular toxicology training. We have opened the Training Grant for University-wide selection to further stimulate interdisciplinary/multidisciplinary approaches in research and training. The request for continuation of NIEHS support is validated by the highly successful nature of our program, the clear demand for our graduates, the strong emphasis we place on leadership skills for our trainees and postdoctoral fellows, the increasing number of students interested in toxicology, substantial institutional commitment, strong and well-funded research programs of our faculty, and the excellence of the training environment.